TAMPA — Dr. Isabelle Roese says she had hoped to make a career of treating unwanted dogs and cats dropped off at Hillsborough County's animal shelter, of "being the voice" for animals by testifying for them in cruelty cases.

But she quit last month after 13 years, citing deteriorating shelter conditions. They include increasing numbers of animals getting sick, dangerous dogs being made available for adoption to families and a lack of professional treatment from new management, she said.

"It was extremely difficult," Roese said. "It was more than work to me, it was a career. It was a close-knit family."

Roese is the second of the shelter's three full-time veterinarians to leave in recent weeks, with both giving similar reasons.

Volunteers and leaders of some animal welfare groups complain of flea-ridden dogs and cats, dirty and overcrowded kennels, and cats displaying obvious signs of illness such as runny eyes and noses. They're circulating a petition asking for shelter management to clean up its act, gathering 600 signatures in a week.

"If the public treated their animals like this, we would be arrested and charged with animal cruelty," said Sandra Pulliam, a board member of the St. Francis Society Animal Rescue, who started the petition.

Ian Hallett, who took over as Animal Services' director 13 months ago, acknowledged an increase in animals getting sick at the shelter, though he was not immediately able to provide exact numbers. But he said it's partly because the shelter has seen a sharp increase in the number of animals overall this summer.

And, unlike in the past, the shelter is operating under new rules that prohibit euthanizing animals that arrive sick. The shelter has also extended hold times in an effort to increase the number of animals that get adopted.

As a result, the shelter has euthanized fewer animals in the past 12 months due to sickness than in the year prior and found homes for 2,000 more animals than last year, he said.

"Hillsborough County Animal Services has traditionally controlled disease through aggressive euthanasia," Hallett said. "When euthanasia is the only way you know how to control disease, you're going to be challenged and have a lot of lessons to be learned in keeping the animals free of disease and keeping the animals alive for adoption and rescue."

As far as dangerous dogs getting adopted, he said the same staffers who gauge aggression are in place from before he was hired and he said he has never gone against their recommendations.

Hallett said he is working on steps to better manage the population, keep sick animals away from healthy ones and implement other preventive measures. He said he is dealing with three vacancies on a shelter staff of 19, as well as the turnover in veterinarians that has forced him to turn to temporary help.

His department also faced sharp budget cuts during the recession, before his arrival, forcing increasing reliance on volunteers — some of whom are now rebelling.

"I think Ian's just in over his head about what to do and not consulting the vets is part of the problem," said Susan Green, a volunteer with the shelter since the outreach program began in 2007. "I was very proud of the shelter at one point."

Hallett's brief tenure has been mired in controversy, much of it not of his making.

The prior director, Bill Armstrong, retired two years ago. Then County Administrator Mike Merrill effectively forced out Armstrong's chief deputy, who was popular with staff, volunteers and many animal-welfare groups, though not all.

County commissioners also latched on to a national trend in approving a plan to make the shelter a no-kill facility, or at least low kill, by taking aggressive steps to increase neutering and get more animals adopted. Merrill hired Hallett, who worked at a no-kill shelter in Austin, Texas, to lead the effort.

In May, Hallett won commission approval for his strategy, called "Be the Way Home." It calls for more creative marketing of shelter animals, mobile adoptions and promotional events, and a controversial program to capture stray cats, neuter them, then let them loose again.

Supporters of the initiative say they hope the overall plan is given a chance to work.

"I'm not suggesting things are ideal or perfect," said Jen Morgan, co-creator of the Urgent Cats Tampa Bay Facebook page, which markets cats available for adoption. "There's definitely a lot of sickness going on. Despite all that, I believe that this plan has the strong potential to fix a lot of these things."

Hallett said he believes part of the concern being voiced is a continuation of the acrimony stirred by the changeover in management and shelter philosophy.

The departing vets say that is not so, as far as it relates to them. Roese said that, while she was disappointed by the change in management, she got past it and was prepared to work with Hallett, but felt he disregarded her professional recommendations. At times, his suggestions ran counter to her veterinary teachings, she said.

Meanwhile, Dr. Nicole Ferguson said she supports the general direction Hallett is trying to take. A veterinarian of 15 years, she was hired by Hallett less than a year ago, but it was only months before she was applying for a new job elsewhere.

She and Roese said they believe the shelter is falling short of its main purpose, which is promoting public health by addressing the number of stray and unwanted animals.

And Ferguson said the lack of communication made it feel like she was not part of a team, let alone a family like Roese described.